Forest Ecosystem Dynamics Multisensor Airborne Campaign (FED MAC):
Bidirectional Reflectance Measurements of Forest Canopy Using PARABOLA
The Biospheric Sciences Branch (formerly Earth Resources Branch)
within the Laboratory for Terrestrial Physics at NASA's Goddard Space
Flight Center and associated University investigators are involved in
a research program entitled Forest Ecosystem Dynamics (FED) which is
fundamentally concerned with vegetation change of forest ecosystems at
local to regional spatial scales (100 to 10,000 meters) and temporal
scales ranging from monthly to decadal periods (10 to 100 years). The
nature and extent of the impacts of these changes, as well as the
feedbacks to global climate, may be addressed through modeling the
interactions of the vegetation, soil, and energy components of the
boreal ecosystem.
The Portable Apparatus for Rapid Acquisition of Bidirectional
Observations of Land and Atmosphere, or PARABOLA instrument
(see Deering and Leone, 1986 for a complete description) was
employed to measure the directional radiances in essentially the
complete 4 pi irradiance field above and below the spruce-hemlock
canopy under cloudless and overcast sky. The PARABOLA is a three-channel
(visible, near infrared, and mid-infrared; 0.650-0.670, 0.810-0.840,
and 1.620-1.690 um, respectively), radiometer with a scanning head
that turns on two axes, which enables the acquisition of radiance data
for almost the complete sky- and ground-looking hemispheres in
15 degrees instantaneous field-of-view sectors in only 11 s.
Measurements were made during the 1989 experiment with the instrument
deployed on the meteorological tower using a 6.5 m triangular truss
boom. To avoid tower shadowing in 1991, a specially contructed 32 m
telescopic mast was supported on a 4 m long by 1.8 m wide,
hollow-frame trailer adapted for mounting the PARABOLA.
The FED Home Page is at: http://forest.gsfc.nasa.gov/.